Context

Urban environments create a wide range of habitats that harbour a great diversity of plant species, many of which are of alien origin. For future urban planning and management of the green areas within the city, understanding of the spatial distribution of invasive alien species is of great importance.

Objectives

Our main aim was to assess how availability of different ecosystem types within a city area, as well as several parameters describing urban structure interact in determining the cover and identity of invasive alien species.

Methods

We studied the distribution of chosen invasive plant species in a mid-sized city in the Czech Republic, central Europe, on a gradient of equal sized cells from the city centre to its outskirts.

Results

A great amount of variation was explained by spatial predictors but not shared with any measured variables. The species cover of invasive species decreased with increasing proportion of urban greenery and distance from the city centre, but increased with habitat richness; road margins, ruderal sites, and railway sites were richest in invasive species. In contrast, the total number of invasive species in cells significantly decreased with increasing distance from the city centre, but increased with habitat richness.

Conclusions

Our results suggest that different invasive species prefer habitats in the vicinity of the city centre and at its periphery and the spatial structure and habitat quality of the urban landscape needs to be taken into account, in efforts to manage alien plant species invasions in urban environments.

Context

The nature of urban ecology theory is controversial. Issues include whether urban theory is distinct, whether it has principles, and whether those principles differ from those for non-urban systems. Recently, Richard Forman enumerated urban ecology principles, while we have previously articulated different urban ecology principles. This raises the question of whether there are legitimately different sets of principles.

Objectives

Recognizing the legitimacy of Forman’s principles, we wish to determine whether different methodological assumptions can lead to different sets of urban ecology principles.

Methods

We contrast Forman’s 90 urban ecology principles with our much smaller set to determine why they differ in detail, empirical motivation, and generality. We identify the approaches that generate each set of principles, and seek an inclusive framework to integrate them.

Results

The alternative sets represent contrasting approaches to identifying principles: Forman’s approach is more inductive, generating principles from a body of empirical cases, while our concise roster is more deductive, focusing on general ideas from which the details of specific cases can be derived. Both are legitimate.

Conclusions

Principles of urban ecology can arise from inductive empirical generalization within specified ecological, cultural, and historical contexts, as shown by Forman. However, urban ecology principles can also emerge from a more general, synthetic impulse as we have shown. Neither approach is necessarily better. Both can contribute to a comprehensive theoretical hierarchy that can advance urban ecology.

Context

Many aquatic communities are linked by the aerial dispersal of multiple, interacting species and are thus structured by processes occurring in both the aquatic and terrestrial compartments of the ecosystem.

Objectives

To evaluate the environmental factors shaping the aquatic macroinvertebrate communities associated with tank bromeliads in an urban landscape.

Methods

Thirty-two bromeliads were georeferenced to assess the spatial distribution of the aquatic meta-habitat in one city. The relative influence of the aquatic and terrestrial habitats on the structure of macroinvertebrate communities was analyzed at four spatial scales (radius = 10, 30, 50, and 70 m) using redundancy analyses.

Results

We sorted 18,352 aquatic macroinvertebrates into 29 taxa. Water volume and the amount of organic matter explained a significant part of the taxa variance, regardless of spatial scale. The remaining variance was explained by the meta-habitat size (i.e., the water volume for all of the bromeliads within a given surface area), the distance to the nearest building at small scales, and the surface area of buildings plus ground cover at larger scales. At small scales, the meta-habitat size influenced the two most frequent mosquito species in opposite ways, suggesting spatial competition and coexistence. Greater vegetation cover favored the presence of a top predator.

Conclusions

The size of the meta-habitat and urban landscape characteristics influence the structure of aquatic communities in tank bromeliads, including mosquito larval abundance. Modifications to this landscape will affect both the terrestrial and aquatic compartments of the urban ecosystem, offering prospects for mosquito management during urban planning.

Context

Efficient restoration of longitudinal river connectivity relies on barrier mitigation prioritization tools that incorporate stream network spatial structure to maximize ecological benefits given limited resources. Typically, ecological benefits of barrier mitigation are measured using proxies such as the amount of accessible riverine habitat.

Objectives

We developed an optimization approach for barrier mitigation planning which directly incorporates the ecology of managed taxa, and applied it to an urbanizing salmon-bearing watershed in Alaska.

Methods

A novel river connectivity metric that exploits information on the distribution and movement of managed taxon was embedded into a barrier prioritization framework to identify optimal mitigation actions given limited restoration budgets. The value of ecological information on managed taxa was estimated by comparing costs to achieve restoration targets across alternative barrier prioritization approaches.

Results

Barrier mitigation solutions informed by life history information outperformed those using only river connectivity proxies, demonstrating high value of ecological information for watershed restoration. In our study area, information on salmon ecology was typically valued at 0.8–1.2 M USD in costs savings to achieve a given benefit level relative to solutions derived only from stream network information, equating to 16–28% of the restoration budget.

Conclusions

Investing in ecological studies may achieve win–win outcomes of improved understanding of aquatic ecology and greater watershed restoration efficiency.

Context

The urban heat island (UHI) affects both biogeochemical cycles and human society. Previous studies of UHI indicate urban expansion and local land-cover change can lead to higher temperatures in cities compared to the adjacent countryside. Few studies have examined the joint effects of city- and local-scale factors on urban warming, and their relative importance.

Objectives

We examined the overall impact of urbanization on urban warming from 1983 to 2011 in Beijing, investigated how city size and the proportion of local developed land jointly influenced the air temperature, and quantified their relative importance over time.

Methods

We compared temperature trends between urban and reference stations and conducted linear regressions to evaluate the city- and local-scale influences, based on meteorological data and remote sensing data.

Results

Urbanization significantly influenced trends of the air temperature, especially in summer. Trends of the mean temperature caused by urbanization was 0.3–0.4 °C decade^?1 yearly and 0.4–0.6 °C decade^?1 in summer. The increase of city size and the proportion of local developed land both contributed to urban warming, but their relative importance changed over time and varied seasonally. The local-scale factor played a vital role for the air temperature when the city size was relatively small, and were more important in summer when there was more greenspace at the local scale. However, the city-scale factor may cause stronger heat stress in summer, if there was less greenspace locally. When the city size was very large, the city-scale factor became the only significant factor affecting the air temperature.

Conclusions

When a city is relatively small, optimizing the composition or configuration of the local land cover could effectively alleviate UHI effects. However, when the city is already large, a more effective way is to control additional sprawl.

Context

Species distributions are driven by a wide variety of abiotic and biotic factors, including nest placement for breeding individuals. As such, the spatial distribution of nests within a landscape can reflect environmental heterogeneity, habitat preferences, or even interactions with predators and other species.

Objectives

We determined the extent to which environmental heterogeneity and predation risk accounted for the observed spatial distribution of nests.

Methods

We assessed the spatial distribution of 112 nests of a migratory shorebird, the Hudsonian Godwit (Limosa haemastica), at Beluga River, Alaska, from 2009 to 2012, and explicitly tested for the relative influence of habitat characteristics and predation risk on nest locations. We also evaluated the effect of nest location, distance to conspecific nests, and proximity to roads on nest fate using 64 nests that were monitored through completion.

Results

Hudsonian Godwit nests were clustered across the landscape despite a lack of significant spatial autocorrelation (i.e., patchiness) in vegetation characteristics at either the micro- or landscape scale. Nest fate also was not predicted by either the distance to the nearest conspecific neighbor or proximity to roads. Thus, neither habitat characteristics nor predation risk explained the clustering of godwit nests.

Conclusions

These results suggest that godwits may select nest locations based more on social cues than underlying heterogeneity in vegetation or predation risk. As such, intra- and inter-specific interactions should be considered when developing management plans for species of conservation concern.

Context

Dispersal has important fitness consequences for individuals, populations, and species. Despite growing theoretical insights into the evolution of dispersal, its behavioral underpinnings remain empirically understudied, limiting our understanding of the extent and impact of responses to landscape-level heterogeneity of environments, and increasing the risk of inferring species-level responses from biased population sampling.

Objectives

We asked if predictable ecological variation among naturally fragmented arid waterbodies is correlated with disparate dispersal responses of populations of the desert goby Chlamydogobius eremius, which naturally inhabits two habitat “types” (permanent springs, ephemeral rivers), and different levels of hydrological connectivity (high and low) that potentially convey different costs and benefits of dispersal.

Methods

To test for possible behavioral divergence between such populations, we experimentally compared the movement behaviors (correlates of emigration and exploration) of wild-caught fish. We used two biologically relevant spatial scales to test movement relevant to different stages of the dispersal process.

Results

Behavior differed at both spatial scales, suggesting that alternative dispersal strategies enable desert gobies to exploit diverse habitat patches. However, while emigration was best predicted by the connectivity (flood risk) of fish habitats, exploration was linked to their habitat type (spring versus river).

Conclusions

Our findings demonstrate that despite a complex picture of ecological variation, key landscape factors have an overarching effect on among-population variation in dispersal traits. Implications include the maintenance of within-species variation, potentially divergent evolutionary trajectories of naturally or anthropogenically isolated populations, and the direction of future experimental studies on the ecology and evolution of dispersal behavior.

Context

The provision of multiple ecosystem services (ES) within a landscape is commonly referred to as landscape multifunctionality. Modifying landscapes to increase multifunctionality and reduce trade-offs with concurrent services bears the potential to enhance sustainability in human-dominated landscapes. Assessing landscape multifunctionality is thus crucial for land management and planning, but lack of a clear definition and operationalization of multifunctionality impedes comparisons of different study results.

Objectives

We want to address how elements of the study design affect results of multifunctionality assessments. Furthermore, we want to quantify future multifunctionality in the European Union (EU) and indicate the role of land use change and land use diversity on multifunctionality.

Methods

We analyzed diverging scenarios depicting land use change in the EU between 2000 and 2040 for their effects on landscape multifunctionality. We tested different multifunctionality indicators at various spatial scales based on the modelling of 12 ES and biodiversity indicators.

Results

Particularly the analysis scale determines the interpretation of landscape multifunctionality. Coldspots identified by different indicators are in higher agreement than hotspots. We could not confirm links between land use diversity and landscape multifunctionality. While, at EU scale, multifunctionality slightly increases in future scenarios, agricultural intensification and (peri-)urban growth pose large threats to multifunctional landscapes.

Conclusions

The choice of indicator and analysis scale strongly determine possible interpretations of the results. Rather than focusing on the impacts of land use change on multifunctionality, it is recommended to base land use policy on the impacts of location-specific change on ES supply and demands.

Context

Environmental processes and dispersal are primary determinants of metacommunity dynamics. The relative importance of these effects may vary between species of different abundance classes, given variation in life history traits. Under high disturbance conditions, rare species may be more easily eliminated from their optimal habitats and their distribution may therefore be more heavily dependent upon dispersal from nearby habitat patches than common species.

Objectives

We tested if metacommunity dynamics vary between abundance classes in a high disturbance environment.

Methods

Standardized butterfly sampling was conducted in the urban parks of Hong Kong. To estimate the strength of environmental processes, we measured an array of environmental variables for all sampled parks. Spatial predictors were generated to estimate the effect of dispersal.

Results

For shaping common species compositions, we found environmental processes (and specifically environmental variables including floral density and surrounding woody plant cover) slightly more important than spatial processes. For rare species, only spatial processes were significant while environmental processes were insignificant. Our result contrasts previous studies in natural metacommunities, which have shown that both common and rare species compositions are shaped by environmental processes and similar variables.

Conclusions

Our results demonstrate that high disturbance conditions may inhibit rare species establishment and persistence in urban landscapes. Local habitat management may not be sufficient in conserving rare species in urban environments—spatial context and configuration should be considered in planning for biodiversity. We also highlight the utility of community deconstruction analysis in providing insights into rare species metacommunity dynamics.

Context

Conservation research often focuses on individual threats at a single spatial scale, but population declines can result from multiple stressors occurring at different spatial scales. Analyses incorporating alternative hypotheses across spatial scales allow more robust evaluation of the ecological processes underlying population declines.

Objectives

Populations of many aerially insectivorous birds are declining, yet conservation efforts remain focused on habitat due to an absence of data on changes in prey availability. We evaluate the potential for prey and habitat availability at multiple spatial scales to influence a population of eastern whip-poor-wills (Antrostomus vociferous).

Methods

We assess relationships between landcover (topographical map and satellite imagery) and insect abundance (moths and beetles from blacklight traps), and whip-poor-will distribution and abundance within eastern Canada using Ontario breeding bird atlas data (1980s and 2000s), acoustic recordings (regional), and point counts (local).

Results

Whip-poor-will occurrence in both atlas time periods was positively associated with forest area and fragmentation, but only a delayed effect of urban area explained reductions in detection. Contemporary regional whip-poor-will presence was positively related to moth abundance, and local whip-poor-will abundance was best predicted by area of open-canopy forest, anthropogenic linear disturbance density, and beetle abundance. Our finding that bird presence and abundance were associated with human activity and insect abundance across spatial scales suggests factors beyond habitat structure are likely driving population declines in whip-poor-wills and other aerial insectivores.

Conclusions

This study demonstrates the importance of examining multiple hypotheses, including seasonally and locally variable food availability, across a range of spatial scales to direct conservation efforts.

Context

Sustaining hydrologic ecosystem services is critical for human wellbeing but challenged by land use for agriculture and urban development. Water policy and management strive to safeguard hydrologic services, yet implementation is often fragmented. Understanding the spatial fit between water polices and hydrologic services is needed to assess the spatial targeting of policy portfolios at landscape scales.

Objectives

We investigated spatial fit between 30 different public water policies and four hydrologic services (surface and groundwater quality, freshwater supply, and flood regulation) in the Yahara Watershed (Wisconsin, USA)—a Midwestern landscape that typifies tensions between agriculture, urban development, and freshwater resources.

Methods

Spatial extent of water policy implementation was mapped, and indicators of hydrologic services were quantified for subwatersheds using empirical estimates and validated spatial models.

Results

We found a spatial misfit between the overall spatial implementation of water policy and regions of water quality concern, indicating a need for better targeting. Water quality policies can also be leveraged to protect other hydrologic services such as freshwater supply and flood regulation. Individual policy application areas varied substantially in their spatial congruence with each hydrologic service, indicating that not all services are protected by a single policy and highlighting the need for a broad spectrum of policies to sustain hydrologic services in diverse landscapes. We also identified where future policies could be targeted for improving hydrologic services.

Conclusions

Joint spatial analysis of policies and ecosystem services is effective for assessing spatial aspects of institutional fit, and provides a foundation for guiding future policy efforts.

Context

Expansion of urban settlements has caused observed declines in ecosystem services (ES) globally, further stressing the need for informed urban development and policies. Incorporating ES concepts into the decision making process has been shown to support resilient and functional ecosystems. Coupling land change and ES models allows for insights into the impacts and anticipated trade-offs of specific policy decisions. The spatial configuration of urbanization likely influences the delivery and production of ES.

Objective

When considering multiple ES simultaneously, improving the production of one ecosystem service often results in the decrease in the provision of other ES, giving rise to trade-offs. We examine the impact of three urban growth scenarios on several ES to determine the degree to which spatial configuration of urbanization and the development of natural land cover impacts these services over 25 years.

Methods

We couple land change and ES models to examine impacts to carbon sequestration, surface water-run off, nitrogen and phosphorus export, organic farming and camping site suitability, to determine trade-offs among the six ES associated with each spatial configuration for western North Carolina.

Results

Consequences of urban configurations are dramatic, with degraded ES across all scenarios and substantial variation depending on urban pattern, revealing trade-offs. Counter-intuitive trade-offs between carbon sequestration and lands available for organic farming and camping were observed, suggesting that no configurations result in mutual benefits for all ES.

Conclusions

By understanding trade-offs associated with urban configurations, decision makers can identify ES critical to an area and promote configurations that enhance those.

Context

The habitat amount hypothesis has rarely been tested on plant communities. It remains unclear how habitat amount affect species richness in habitat fragments compared to island effects such as isolation and patch size.

Objectives

How do patch size and spatial distribution compared to habitat amount predict plant species richness and grassland specialist plant species in small grassland remnants? How does sampling area affect the prediction of spatial variables on species richness?

Methods

We recorded plant species density and richness on 131 midfield islets (small remnants of semi-natural grassland) situated in 27 landscapes in Sweden. Further, we tested how habitat amount, compared to focal patch size and distance to nearest neighbor predicted species density and richness of plants and of grassland specialists.

Results

A total of 381 plant species were recorded (including 85 grassland specialist species). A combination of patch size and isolation was better in predicting both density and richness of species compared to habitat amount. Almost 45% of species richness and 23% of specialist species were explained by island biogeography parameters compared to 19 and 11% by the amount of habitat. A scaled sampling method increased the explanation level of island biogeography parameters and habitat amount.

Conclusions

Habitat amount as a concept is not as good as island biogeography to predict species richness in small habitats. Priority in landscape planning should be on larger patches rather than several small, even if they are close together. We recommend a sampling area scaled to patch size in small habitats.

Context

Large datasets that exhibit residual spatial autocorrelation are common in landscape ecology, introducing issues with model inference. Computationally intensive statistical techniques such as simultaneous autoregression (SAR) are used to provide credible inference, yet landscape studies make choices about autocorrelation structure and data reduction techniques without adequate understanding of the consequences for model estimation and inference.

Objectives

Our goal is to understand the effects of misspecification of neighborhood size, subsampling, and data partitioning on SAR estimation and inference.

Methods

We use remotely sensed burn severity for a large wildfire in north-central Washington State as a case study. First we estimate SAR for remotely sensed burn severity data at multiple subsampling intensities, data partitions, and neighborhood distances. Second, we simulate landscape burn severity data with SAR errors and calculate type I error rates for SAR estimated at the simulation neighborhood distance, and at misspecified neighborhood distances.

Results

Subsampling and misspecification of the neighborhood result in spurious inference and modified coefficient estimates. Type I error rates are close to the specified α-level when the model is estimated at both the simulation neighborhood and the distance that minimizes AIC.

Conclusions

By evaluating the effectiveness of pre-burn fuel reduction treatments on subsequent wildfire burn severity, we demonstrate that misspecification of the neighborhood distance and subsampling the data compromises inference and estimation. Using AIC to choose the neighborhood distance provides type I error rates near the stated α-level in simulated data.

Context

Regime shifts are well known for driving penetrating ecological change, yet we do not recognise the consequences of these shifts much beyond species diversity and productivity. Sound represents a multidimensional space that carries decision-making information needed for some dispersing species to locate resources and evaluate their quantity and quality.

Objectives

Here we assessed the effect of regime shifts on marine soundscapes, which we propose has the potential function of strengthening the positive or negative feedbacks that mediate ecosystem shifts.

Methods

We tested whether biologically relevant cues are altered by regime shifts in kelp forests and seagrass systems and how specific such shifted soundscapes are to the type of driver; i.e. local pollution (eutrophication) vs. global change (ocean acidification).

Results

Here, we not only provide the first evidence for regime-shifted soundscapes, but also reveal that the modified cues of shifted ecosystems are similar regardless of spatial scale and type of environmental driver. Importantly, biological sounds can act as functional cues for orientation by dispersing larvae, and observed shifts in soundscape loudness may alter this function.

Conclusions

These results open the question as to whether shifted soundscapes provide a functional role in mediating the positive or negative feedbacks that govern the arrival of species associated with driving change or stasis in ecosystem state.

Context

Species distributions are a function of an individual’s ability to disperse to and colonize habitat patches. These processes depend upon landscape configuration and composition.

Objectives

Using Blanchard’s cricket frogs (Acris blanchardi), we assessed which land cover types were predictive of (1) presence at three spatial scales (pond-shed, 500 and 2500 m) and (2) genetic structure. We predicted that forested, urban, and road land covers would negatively affect cricket frogs. We also predicted that agricultural, field, and aquatic land covers would positively affect cricket frogs.

Methods

We surveyed for cricket frogs at 28 sites in southwestern Ohio, USA to determine presence across different habitats and analyze genetic structure among populations. For our first objective, we examined if land use (crop, field, forest, and urban habitat) and landscape features (ponds, streams, and roads) explained presence; for our second objective, we assessed whether these land cover types explained genetic distance between populations.

Results

Land cover did not have a strong influence on cricket frog presence. However, multiple competing models suggested effects of roads, streams, and land use. We found genetic structuring: populations were grouped into five major clusters and nine finer-scale clusters. Highways were predictive of increased genetic distance.

Conclusions

By combining a focal-patch study with landscape genetics, our study suggests that major roads and waterways are key features affecting species distributions in agricultural landscapes. We demonstrate that cricket frogs may respond to landscape features at larger spatial scales, and that presence and movement may be affected by different environmental factors.